1. Field of Invention
This invention relates to surface deformation type wavefront phase modulators.
2. Prior Art
Prior art surface deformation type wavefront phase modulators have suffered from a multitude of problems. Devices which utilize a reflective deformable surface are plagued by the complications cited in U.S. Pat. No. 4,879,602 to Glenn, Nov. 7, 1989. As identified by Glenn, tradeoffs involving reflectivity and conductor thickness, a compromise inherent with the utilization of deformable reflectors, adversely effects performance. In addition, intrusion of the incident light onto the control mechanism presents additional problems associated with the utilization of deformable reflectors.
Previous alternatives to the utilization of a deformable reflector include the device described in the article titled "Deformable Surface Spatial Light Modulator" by K, Hess et al, Optical Engineering May 1987, Vol. 26, No. 5. and the device described in U.S. Pat. No. 3,835,346 to Mast et al, Sep. 10, 1974. Configurations which rely upon a separation gap between the deformable media and a control mechanism suffer from several complications. As identified in the article titled "Viscoelastic Control Layers for Solid-State Light Valves" by R. Tepe, et al, SPIE Vol. 684 Liquid Crystals and Spatial Light Modulators Materials, 1986, page 27, such gaps must be very thin and extremely parallel.
In addition, as identified in the article titled "Deformation Behavior of Thin Viscoelastic Layers Used in an Active Matrix Addressed Spatial Light Modulator" by W. Brinker et al SPIE Vol. 1018 Electro-Optic and Magnetic Materials 1988, page 82, elastic electrodes affixed to the deformable media layer leads to a faster response time. Such considerations are important for real time operation of phase modulators.
Additional surface deformation type wavefront phase modulators include the device described in U.S. Pat. No. 4,494,826 to Smith, Jan. 22, 1985. In U.S. Pat. No. 4,494,826 the read light is reflected by a deformable reflective conductor. As such, this device is plagued by the compromises identified in U.S. Pat. No. 4,879,602 to Glenn. In addition, by failing to allow the read light to be reflected from within the deformable media, U.S. Pat. No. 4,494,826 fails to achieve the advantages inherent to applicant's invention.
Accordingly, a need exists for a device which overcomes the limitations of prior art.